1. Field of the Invention
The present invention relates in general to a disk drive apparatus attachment structure and attachment method, and more particularly, to a disk drive apparatus attachment structure and attachment method for attaching a spindle motor and disks to a disk drive apparatus.
2. Description of Related Art
Recently, in disk drive apparatuses such as hard disk drives, it is generally seen as a product lineup to use one and the same enclosure case and to provide products with a single disk enclosed in the enclosure case and products with two (or more) disks enclosed in the enclosed case. In these disk drive apparatuses, since a mechanical resonance frequency of the enclosure case greatly affects the stability of its head during track following, a mechanical resonance frequency must be so designed as to be the same for the one-disk version as for the two-disk (or not less than three) version.
For this reason, in conventional disk drive apparatus attachment structures, there are, for instance, two types: one where a two-disk version is set in the basic design and one dummy disk is added for the one-disk version; and the other where the shaft rigidity of the spindle motor for the one-disk version is deliberately lowered to be the same as for a two-disk version.
However, on the one hand, since originally unnecessary parts come to be used as dummy disks, the number of parts increases, thereby causing waste. On the other hand, to change the shaft rigidity of the spindle motor results in the provision of several types of parts which dispense originally with one type.
In this way, conventional disk drive apparatus attachment structures have problems in that the cost increases and the number of parts to be controlled becomes larger.
It can be seen then that there is a need for a disk drive apparatus attachment structure, a disk drive apparatus, and a disk drive apparatus attachment method wherein, even when varying the number of disks, the instability of the track following of the magnetic head can be prevented using one and the same enclosure case in a product lineup.